1. Field of the Invention
The present invention relates to a scroll type compressor for sucking, compressing and discharging fluid, more particularly, the construction of the spiral elements thereof.
2. Description of Related Art
A scroll type compressor, as known well, compresses fluid in a manner that the volume of the operation chamber, which is constituted by bringing a movable scroll spiral element into contact with a fixed scroll spiral element, is reduced according to the rotation of the movable scroll spiral element. However, due to a fabrication error on manufacturing the respective spiral elements or a deformation of the spiral elements by compression reaction and thermal expansion, there may cause a problem that both spiral elements come to an insufficient contact with each other and fluid leaks to a lower pressure side between the adjacent operation chambers.
To cope with this problem, it has been proposed, as described in JP-A-57-62988 and Jp-A-58-13184, that the dimensions of the respective spiral elements are designed to ensure the accurate contact of both the spiral elements within an angle of 360 degrees from the spiral starting point and the spiral elements are provided with relief after the angle of 360 degrees to prevent the possible contact of the spiral elements.
However, when both the spiral elements come to the positive contact within the range of the center portions of the spiral elements, lubricant oil tends to be compressed at the operation chamber at the center portions where the volume is reduced and so called "liquid compression" may occur. Further, there is a fear that the spiral elements may be broken down by an excessive pressure increase of the operation chamber, because the compression reaction becomes larger as the operation chamber is located more nearly to the center portion.